Dynamics of localized spins coupled to the conduction electrons with charge/spin currents

The effects of the charge/spin currents of conduction electrons on the dynamics of the localized spins are studied in terms of the perturbation in the exchange coupling $J_{K}$ between them. The equations of motion for the localized spins are derived exactly up to $O(J_{K}^2)$, and the equations for the two-spin system is solved numerically. It is found that the dynamics depends sensitively upon the relative magnitude of the charge and spin currents, i.e., it shows steady state, periodic motion, and even chaotic behavior. Extension to the multi-spin system and its implications including possible ``spin current detector'' are also discussed.Comment: 5 pages, 4 figures, REVTe

South-South education relations

While scholarly interest in South–South cooperation (SSC) has substantially grown over the past decade, South–South education relations have received only scant attention in the Anglophone academic literatures on SSC, international development and international and comparative education. This chapter adopts an historical and global approach to this topic in an effort to contribute to closing this research gap. The chapter unfolds as follows: the first section introduces the concepts of ‘the South’ and ‘South–South cooperation’, counter-posed with practices of ‘triangular collaboration’ and ‘best practice transfer’. On this basis, the second section conducts a critical review of existing South–South education cooperation literatures. Framed by these discussions, two case studies of contemporary South–South education relations are presented: the ¡Yo, Sí Puedo! (Sure, I Can!) global literacy campaign promoted by the governments of the Republic of Cuba and the Bolivarian Republic of Venezuela; and the education cooperation agenda of the so-called BRICS. The conclusion resumes the question of whether South–South education cooperation simply represents ‘best practice transfer’ or Third World solidarity for global transformation, while proposals for a future research agenda are developed.info:eu-repo/semantics/acceptedVersio

An improved method for high-quality RNA isolation from needles of adult maritime pine trees

Conventional RNA isolation methods optimised for pine seedlings have been shown to produce poor quality RNA when applied to needles of adult pine trees. We describe here a modified procedure to isolate high pure RNA from needles of thirty-year-old maritime pines, exhibiting high levels of phenolics, polysaccharides and RNases. Major changes were the inclusion of proteinase K in the extraction medium followed by incubation at 42°C. Integrity and purity were evaluated by denaturing gel electrophoresis and by spectrophotometry (A260/A230 and A260/A280). Total RNA could be successfully used for poly(A)+-RNA isolation and cDNA library construction.Fundação para a Ciência e a Tecnologia (FCT) - grant ref. SFRH/BD/3194/2000

Molecular aproach on the study of infection of Pinus pinaster Ait. by the fungus Lophodermium seditiosum

Poster apresentado no 10th International Congress on Molecular Plant-Microbe Interactions, Madison, Wisconsin, Estados Unidos da América.The fungi genus Lophodermium comprises several species known to intervene in the degradation process of pine needles. Amongst these species, only L. seditiosum is known to be pathogenic, as it is able to infect healthy needles in young pine populations, spreading from stomata and leading to the death of the needle (needle cast disease). Maritime pine (Pinus pinaster, Ait) is one of the most relevant forest species in SW Europe. Needle cast disease, by attacking young plants, leads to two main events: the lack of self regeneration in natural populations, and complete destruction of pine nurseries. The purpose of our study is to understand the nature of the infection of Pinus pinaster Ait. by L. seditiosum and ultimately gain some knowledge on the overall response of Conipherophyta to infection. As a first step towards this goal, a cDNA library of Pinus pinaster was constructed. Subsequent effort has been directed towards the screening of genes encoding PR proteins involved in host-pathogen interaction, as well as oxidative stress enzymes. In addition, PCR amplification using degenerate primers is in progress in order to allow the identification of putative Resistance genes.Fundação para a Ciência e a Tecnologia (FCT) - grant ref. SFRH/BD/3194/200

Charge pumping in magnetic tunnel junctions: Scattering theory

We study theoretically the charge transport pumped by magnetization dynamics through epitaxial FIF and FNIF magnetic tunnel junctions (F: Ferromagnet, I: Insulator, N: Normal metal). We predict a small but measurable DC pumping voltage under ferromagnetic resonance conditions for collinear magnetization configurations, which may change sign as function of barrier parameters. A much larger AC pumping voltage is expected when the magnetizations are at right angles. Quantum size effects are predicted for an FNIF structure as a function of the normal layer thickness.Comment: 4 pages, 3 figures. to be published on Physical Review B Rapid Communicatio

China's wind electricity and cost of carbon mitigation are more expensive than anticipated

The success of China's transition to a low-carbon energy system will be key to achieve the global level of emissions reductions needed to avoid large negative consequences from climate change. China is undergoing an impressive build up of renewable capacity, in particular wind. Using data from the Clean Mechanism Development project database between 2004 and 2012, this study shows that while China made progress in bringing down the levelized cost of wind electricity and cost of carbon mitigation (CCM), serious grid-connection issues and high wind curtailment rates resulted in a levelized cost of wind electricity that is one-half to two times higher than expected, and a CCM that is four to six times higher. Sharp drop in electricity demand, utilization rate, and coal prices in recent years may lead to even higher results.info:eu-repo/semantics/publishedVersio

China's wind industry: leading in deployment, lagging in innovation

China's massive carbon emissions and air pollution concerns have led its government to embrace clean energy innovation as a means of transitioning to a more sustainable energy system. We address the question of whether China's wind industry has become an important source of clean energy technology innovation. We find that in terms of wind capacity expansion, China has delivered enormous progress, increasing its wind capacity from virtually no wind capacity in the early 2000s to 140 GW by 2015. However, in terms of innovation and cost competitiveness, the outcomes were more limited: Chinese wind turbine manufacturers have secured few international patents and achieved moderate learning rates compared to the global industry's historical learning rate. Leading China-based indigenous producers are likely to remain important global players for the foreseeable future, but further progress in reducing the cost of capital equipment may slow relative to the recent past. However, opportunities in lowering curtailment rates and improving turbine quality can reduce China's overall levelized cost of electricity for wind.info:eu-repo/semantics/publishedVersio

Transcriptome of Quercus suber challenged by drought, salinity, and oxidative stresses

Comunicação em painelThe cork oak (Quercus suber) forest (the “montado”) is a unique and emblematic resource for Portugal, due to its ecological, socio-economic significance, and the commercial value of cork. Plant abiotic stresses, particularly reduced water availability and extreme temperatures, are substantial constraints to agricultural and agro-forestry production. In the particular case of cork oak, the damaging land-use policies, the climate change, and imposition of abiotic stresses related with high light intensities have been threatening the cork oak forests. The adaptation to abiotic stresses comprises a series of morphological, physiological, biochemical and molecular changes controlled by complex molecular networks. Recent advances in increasing plant tolerance were achieved after the identification of specific genes suited for plant genetic engineering. However, as abiotic stress is commonly present in the field as a combination of different stresses, the complex plant response mechanisms are far from being elucidated. This work is part of a coordinated effort to uncover the transcriptome of Q. suber and attention was paid to the identification of expressed sequence tags (ESTs) involved in responses to distinct abiotic stress challenges, namely drought, salt and oxidative stresses.This work was supported by the FCT project SOBREIRO/0033/200

Potencial forrageiro de espécies para cultivo no período de safrinha em solos de tabuleiros costeiros.

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